On-vehicle display controller, on-vehicle display system, on-vehicle display control method, and non-transitory storage medium

ABSTRACT

There is provided an on-vehicle display controller including a video data acquiring unit configured to acquire captured video data obtained through imaging by an imager that is configured to image surroundings of a vehicle, a detecting unit configured to detect at least one following vehicle in the captured video data, an identifying unit configured to identify a lower part of the following vehicle detected by the detecting unit, a display video data generating unit configured to set a clipping area of the captured video data so as to include the lower part of the following vehicle identified by the identifying unit, and generate display video data by performing clipping the clipping area from the captured video data, and a display controller configured to cause a display used in the vehicle to display the display video data generated by the display video data generating unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/JP2017/015196, filed on Apr. 13, 2017 which claims the benefit ofpriority of the prior Japanese Patent Application No. 2016-137715, filedon Jul. 12, 2016 and Japanese Patent Application No. 2017-059082, filedon Mar. 24, 2017, the entire contents of which are incorporated hereinby reference.

FIELD

The present application relates to an on-vehicle display controller, anon-vehicle display system, an on-vehicle display control method, and anon-transitory storage medium.

BACKGROUND

A technology for what is called an electronic rearview mirror thatdisplays video from an imager, which images a rear surrounding area of avehicle, instead of a rear view mirror for checking a rear side of thevehicle has been known (for example, see Japanese Laid-open PatentPublication No. 2014-235639 and Japanese Patent No. 5136071).

Incidentally, it has been known that a distance to an object located ata short distance of about 10 meters (m) is recognized using an eyeconvergence angle or eye focus adjustment. Further, it has been knownthat the distance is recognized by comparing sizes or relationships ofthe objects and other surrounding objects.

However, since the electronic rearview mirror displays a real image oftwo-dimensional video in contrast to an optical rearview mirror, it isdifficult to recognize a distance to an object using an eye convergenceangle or eye focus adjustment. Further, in the technologies described inJapanese Laid-open Patent Publication No. 2014-235639 and JapanesePatent No. 5136071, the imager is arranged at a rear end of a vehicle oran inner rear end of the vehicle. Therefore, a mounting position of theimager is closer to a following vehicle than a mounting position of theoptical rearview mirror, so that when the following vehicle approaches,a bottom end of the following vehicle and a road are not displayed onthe electronic rearview mirror. In this manner, when the followingvehicle approaches, it may be difficult to recognize a distance to thefollowing vehicle with the use of the electronic rearview mirror.

SUMMARY

An on-vehicle display controller, an on-vehicle display system, anon-vehicle display control method, and a non-transitory storage medium

According to one aspect, there is provided an on-vehicle displaycontroller comprising: a video data acquiring unit configured to acquirecaptured video data obtained through imaging by an imager that isconfigured to image surroundings of a vehicle; a detecting unitconfigured to detect at least one following vehicle in the capturedvideo data; an identifying unit configured to identify a lower part ofthe following vehicle detected by the detecting unit; a display videodata generating unit configured to set a clipping area of the capturedvideo data so as to include the lower part of the following vehicleidentified by the identifying unit, and generate display video data byperforming clipping the clipping area from the captured video data; anda display controller configured to cause a display used in the vehicleto display the display video data generated by the display video datagenerating unit.

According to one aspect, there is provided an on-vehicle display systemcomprising: the on-vehicle display controller described above; and atleast one of the imager and the display.

According to one aspect, there is provided an on-vehicle display controlmethod comprising steps of: acquiring captured video data obtainedthrough imaging by an imager that is configured to image surroundings ofa vehicle; detecting at least one following vehicle in the capturedvideo data; identifying a lower part of the following vehicle detectedat the detecting; setting a clipping area of the captured video data soas to include the lower part of the following vehicle identified at theidentifying; generating display video data by performing clipping theclipping area from the captured video data; and causing a display usedin the vehicle to display the display video data generated at thegenerating.

According to one aspect, there is provided a non-transitory storagemedium that stores a program for causing a computer serving as anon-vehicle display controller to execute steps of: acquiring capturedvideo data obtained through imaging by an imager that is configured toimage surroundings of a vehicle; detecting at least one followingvehicle in the captured video data; identifying a lower part of thefollowing vehicle detected at the detecting; setting a clipping area ofthe captured video data so as to include the lower part of the followingvehicle identified at the identifying; generating display video data byperforming clipping the clipping area from the captured video data; andcausing a display used in the vehicle to display the display video datagenerated at the generating.

The above and other objects, features, advantages and technical andindustrial significance of this application will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a configuration example of anon-vehicle display system according to a first embodiment;

FIG. 2 is a schematic diagram illustrating a configuration example ofthe on-vehicle display system according to the first embodiment;

FIG. 3 is a block diagram illustrating a configuration example of theon-vehicle display system according to the first embodiment;

FIG. 4 is a diagram illustrating an example of captured video dataobtained through imaging by an imager of the on-vehicle display systemaccording to the first embodiment;

FIG. 5 is a diagram illustrating an example of video displayed on arearview monitor of the on-vehicle display system according to the firstembodiment;

FIG. 6 is a schematic diagram illustrating another configuration exampleof the on-vehicle display system according to the first embodiment;

FIG. 7 is a flowchart illustrating a flow of a process performed by acontroller of an on-vehicle display controller of the on-vehicle displaysystem according to the first embodiment;

FIG. 8 is a diagram illustrating another example of captured video dataobtained through imaging by the imager of the on-vehicle display systemaccording to the first embodiment;

FIG. 9 is a diagram illustrating another example of video displayed onthe rearview monitor of the on-vehicle display system according to thefirst embodiment;

FIG. 10 is a diagram illustrating an example of video displayed on therearview monitor;

FIG. 11 is a block diagram illustrating a configuration example of anon-vehicle display system according to a second embodiment;

FIG. 12 is a flowchart illustrating a flow of a process performed by acontroller of an on-vehicle display controller of the on-vehicle displaysystem according to the second embodiment;

FIG. 13 is a flowchart illustrating a flow of a process performed by acontroller of an on-vehicle display controller of an on-vehicle displaysystem according to a third embodiment;

FIG. 14 is a diagram illustrating an example of captured video dataobtained through imaging by an imager of the on-vehicle display systemaccording to the third embodiment;

FIG. 15 is a diagram illustrating an example of video displayed on arearview monitor of the on-vehicle display system according to the thirdembodiment;

FIG. 16 is a diagram illustrating another example of video displayed onthe rearview monitor of the on-vehicle display system according to thethird embodiment;

FIG. 17 is a diagram illustrating an example of captured video dataobtained through imaging by an imager of an on-vehicle display systemaccording to a fourth embodiment;

FIG. 18 is a flowchart illustrating an example of a flow of a processperformed by a controller of an on-vehicle display controller of theon-vehicle display system according to the fourth embodiment;

FIG. 19 is a flowchart of illustrating another example of a flow of theprocess performed by the controller of the on-vehicle display controllerof the on-vehicle display system according to the fourth embodiment;

FIG. 20 is a diagram illustrating an example of captured video dataobtained through imaging by an imager of an on-vehicle display systemaccording to a fifth embodiment; and

FIG. 21 is a flowchart illustrating an example of a flow of a processperformed by a controller of an on-vehicle display controller of theon-vehicle display system according to the fifth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of an on-vehicle display controller 10, an on-vehicledisplay system 1, an on-vehicle display control method, and anon-transitory storage medium according to the present application willbe described in detail below with reference to the accompanyingdrawings. The present application is not limited by the embodimentsbelow.

First Embodiment

The on-vehicle display system 1 is mounted on a vehicle 100 and displayssurroundings of the vehicle. FIG. 1 is a schematic diagram illustratinga configuration example of the on-vehicle display system according to afirst embodiment. FIG. 2 is a schematic diagram illustrating aconfiguration example of the on-vehicle display system 1 according tothe first embodiment. FIG. 3 is a block diagram illustrating aconfiguration example of the on-vehicle display system 1 according tothe first embodiment.

As illustrated in FIG. 1 to FIG. 3, the on-vehicle display system 1includes an imager 2, a rearview monitor (display) 3, the on-vehicledisplay controller 10, and a recognition dictionary storage 200. In thefirst embodiment, the rearview monitor 3 will be described. However, thedisclosure is applicable to monitors that display video obtained byimaging a front side, a right side, and a left side, or side viewmonitors serving as door mirrors that display video obtained by imaginga right rear side and a left rear side of the vehicle 100.

The imager 2 is arranged on a rear part of the vehicle 100 and images arear side of the vehicle 100. The imager 2 is arranged on, for example,an upper rear end inside the vehicle 100 or a rear end of a vehiclebody. In the first embodiment, the imager 2 is arranged on an upper partof a rear window that is the upper rear end inside the vehicle 100. Whenthe imager 2 is arranged on the upper rear end inside the vehicle 100, amounting position of the imager 2 is located closer to a mountingposition of an optical rearview mirror by 10 centimeters (cm) to 1 m ascompared to a case where the imager is mounted on the rear part of thevehicle body. In other words, an imaging position of captured video data110A obtained through imaging by the imager 2 is close to a viewpoint ofthe optical rearview mirror. Accordingly, a difference between therearview by the captured video data 110A and the rear view by an opticalrearview mirror can be reduced. Further, when the imager 2 is arrangedon the upper rear end inside the vehicle 100, the mounting position ofthe imager 2 is located on the upper side as compared to a case wherethe imager 2 is mounted on the rear part of the vehicle body. Therefore,it becomes possible to easily image a far rear side.

The imager 2 images an area including an area to be checked by therearview monitor 3. A horizontal angle of view of the imager 2 is, forexample, 30° to 60°, and a vertical angle of view of the imager 2 is,for example, 5° to 20°. Specifically, the imager 2 captures the capturedvideo data 110A as illustrated in FIG. 4. FIG. 4 is a diagramillustrating an example of the captured video data obtained throughimaging by the imager 2 of the on-vehicle display system 1 according tothe first embodiment. The imager 2 is capable of capturing video in awider area than the area displayed on the rearview monitor 3. However,an area that allows a driver of the vehicle 100 to appropriatelyrecognize the rear side using the rearview monitor 3 is clipped as aclipping area, and displayed on the rearview monitor 3. The capturedvideo data 110A includes the clipping area that is the area to bechecked by the rearview monitor 3. In the first embodiment, the capturedvideo data 110A includes an area outside the clipping area. In otherwords, the imager 2 normally images an area that is not displayed on therearview monitor 3. The captured video data 110A includes, for example,1920 pixels in the horizontal direction and 1080 pixels in the verticaldirection. The imager 2 outputs the captured video data 110A obtained byimaging to a video data acquiring unit 31 of the on-vehicle displaycontroller 10.

The rearview monitor 3 is, for example, an electronic rearview mirror.When the rearview monitor 3 is used as an electronic rearview mirror, itdoes not matter whether a half mirror for checking the rear side usingoptical reflection is provided or not therein. The rearview monitor 3is, for example, a display including a liquid crystal display (LCD), anorganic electro-luminescence (EL) display, or the like.

The rearview monitor 3 displays video of the rear side of the vehicle100 based on a video signal output from a display controller 35 of theon-vehicle display controller 10. Specifically, the rearview monitor 3displays rear video as illustrated in FIG. 5. FIG. 5 is a diagramillustrating an example of video displayed on the rearview monitor 3 ofthe on-vehicle display system 1 according to the first embodiment. Therearview monitor 3 is arranged at a certain position that can easily beviewed by the driver. In the first embodiment, the rearview monitor 3 isarranged in an upper central part of a windshield S in a vehicle-widthdirection. As illustrated in FIG. 6, the rearview monitor 3 may bearranged in an upper central part of a dashboard D in the vehicle-widthdirection. FIG. 6 is a schematic diagram illustrating anotherconfiguration example of the on-vehicle display system 1 according tothe first embodiment.

When the rearview monitor 3 is used as a safety component of the vehicle100 like the electronic rearview mirror, the rearview monitor 3 ismounted in a fixed manner in front of the driver. When the rearviewmonitor 3 is used not as the safety component but as an auxiliary devicefor checking a rear side, the rearview monitor 3 is not necessarilyarranged in front of the driver, but may be arranged at a certainposition that is appropriate for the driver to view when the driver usesthe rearview monitor 3.

The recognition dictionary storage unit 200 stores therein, for example,a recognition dictionary that enables checking of patterns, such asshapes of front views etc., sizes, and colors of moving objectsincluding four-wheel vehicles, two-wheel vehicles, and persons. Therecognition dictionary storage unit 200 is, for example, a semiconductormemory device, such as a random access memory (RAM), a read only memory(ROM), or a flash memory, or a storage device, such as a hard disk, anoptical disk, or an external storage device over a network.

Referring back to FIG. 3, the on-vehicle display controller 10 includesa storage 20 and a controller 30.

The storage 20 stores therein data needed for various processesperformed in the on-vehicle display controller 10, and also storestherein results of the various processes. The storage 20 is, forexample, a semiconductor memory device, such as a RAM, a ROM, or a flashmemory, or a storage device, such as a hard disk, an optical disk, or anexternal storage device over a network. Alternatively, an externalstorage device wirelessly connected via a communication device (notillustrated) may be used.

The controller 30 is, for example, an arithmetic processing deviceconfigured by a central processing unit (CPU) or the like. Thecontroller 30 includes the video data acquiring unit 31, a detectingunit 32, an identifying unit 33, a display video data generating unit34, and the display controller 35. The controller 30 executes commandsincluded in programs stored in the storage unit 20.

The video data acquiring unit 31 acquires video obtained by imaging therear side of the vehicle 100. The video data acquiring unit 31 acquiresthe captured video data 110A output from the imager 2. The video dataacquired by the video data acquiring unit 31 is, for example, video dataincluding consecutive images at 60 frames per second. The video dataacquiring unit 31 outputs the acquired captured video data 110A to thedetecting unit 32.

The detecting unit 32 detects at least one following vehicles V in thecaptured video data 110A. The detecting unit 32 performs a vehiclerecognition process on the captured video data 110A and detects thefollowing vehicle V. More specifically, the detecting unit 32 performspattern matching on the captured video data 110A using the recognitiondictionary stored in the recognition dictionary storage unit 200, anddetects the following vehicle V. The detecting unit 32 tracks thedetected following vehicle V by image processing. The detecting unit 32outputs detection results to the identifying unit 33.

The identifying unit 33 identifies a lower end portion B as a lower partof the following vehicle V that is detected by the detecting unit 32 inthe captured video data 110A. More specifically, the identifying unit 33identifies ground contact portions of front wheels of the followingvehicle V in the captured video data 110A, or identifies a lower edge ofa body of the following vehicle V in the captured video data 110A. Inthe first embodiment, the identifying unit 33 identifies the groundcontact portions of the front wheels of the following vehicle V in thecaptured video data 110A. In the first embodiment, when the groundcontact portions of the front wheels of the following vehicle V are notidentified, the identifying unit 33 identifies the lower edge of thebody of the following vehicle V in the captured video data 110A. Theidentifying unit 33 tracks the identified lower end portion B of thefollowing vehicle V by image processing. The identifying unit 33 outputsprocessing results to the display video data generating unit 34.

In the first embodiment, an example will be described in which the lowerend portion B of the following vehicle V is used as the lower part. Thelower end portion B of the following vehicle V is a lower edge positionof a shape of the following vehicle V detected by the detecting unit 32.For example, the lower end portion B of the following vehicle V is loweredges of wheels of the following vehicle V. The lower edges of thewheels of the following vehicle V are detected as a straight line. Whenthe wheels or the lower edges of the wheels of the following vehicle Vdo not appear in the captured video data 110A or when the wheels or thelower edges of the wheels of the following vehicle V are notappropriately recognized by image processing, the lower edge of the bodyof the following vehicle V may be used as the lower end portion B of thefollowing vehicle V, for example.

When the detecting unit 32 detects a plurality of following vehicles Vin the captured video data 110A, the identifying unit 33 identifies thelower end portion B of the following vehicle V that meets apredetermined condition. In the first embodiment, the identifying unit33 identifies the lower end portion B of the following vehicle V that islocated at the shortest distance from the vehicle 100 in the capturedvideo data 110A. Further, in the first embodiment, the identifying unit33 identifies the lower end portion B of the following vehicle V that islocated in the most central portion in the captured video data 110A.With this operation, the on-vehicle display system 1 can identify thelower end portion B of the following vehicle V that needs to be checkedon a priority basis, such as the closest one, from among the pluralityof detected following vehicles V.

When the detecting unit 32 detects a plurality of following vehicles Vin the captured video data 110A, the identifying unit 33 adopts, as thefollowing vehicle V located at the shortest distance from the vehicle100, the following vehicle V whose ground contact position is located inthe lowest part in the captured video data 110A among the plurality ofthe detected following vehicles V. Further, when the detecting unit 32detects the plurality of the following vehicles V in the captured videodata 110A, the identifying unit 33 adopts, as the following vehicle Vlocated in the most central portion in the captured video data 110A, thefollowing vehicle V whose position in the width direction is located inthe most central portion in the captured video data 110A among theplurality of the detected following vehicles V. The identifying unit 33may identify the following vehicle V that needs to be checked on apriority basis, based on a plurality of conditions as described above orbased on conditions including a size of the following vehicle V in thewidth direction or the like.

The display video data generating unit 34 sets a clipping area of thecaptured video data 110A so as to include the lower end portion B of thefollowing vehicle V identified by the identifying unit 33, and generatesdisplay video data 110B by performing clipping from the captured videodata 110A. The display video data generating unit 34 outputs the clippeddisplay video data 110B to the display controller 35.

More specifically, the display video data generating unit 34 determineswhether the lower end portion B of the following vehicle V, which isidentified by the identifying unit 33, is deviated from a first clippingarea A1 (a clipping area set in advance) in the captured video data110A. In other words, the display video data generating unit 34determines whether the lower end portion B of the following vehicle V inthe captured video data 110A is located outside the first clipping areaA1. The first clipping area A1 is registered and stored in advance. Inthe first embodiment, it is assumed that the first clipping area A1 is acentral portion of the captured video data 110A.

If the lower end portion B of the following vehicle V in the capturedvideo data 110A is located inside the first clipping area A1 of thecaptured video data 110A, the display video data generating unit 34determines that the lower end portion B is not deviated from the firstclipping area A1. If it is determined that the lower end portion B ofthe following vehicle V is not deviated from the first clipping area A1,the display video data generating unit 34 sets the first clipping areaA1 as the clipping area.

If the lower end portion B of the following vehicle V in the capturedvideo data 110A is located outside the first clipping area A1 of thecaptured video data 110A, the display video data generating unit 34determines that the lower end portion B is deviated from the firstclipping area A1. If it is determined that the lower end portion B ofthe following vehicle V is deviated from the first clipping area A1, thedisplay video data generating unit 34 sets a second clipping area A2,which includes the lower end portion B of the following vehicle V, asthe clipping area. The second clipping area A2 is an area obtained byshifting the first clipping area A1 downward. In the first embodiment,the second clipping area A2 is set so as to include a predeterminednumber of pixels that are present below the lower end portion B of thevehicle. For example, the second clipping area A2 is set so as toinclude 50 pixels that are present below the lower end portion B of thefollowing vehicle V. Alternatively, the second clipping area A2 may beset so as to include a road surface at the lower end portion B of thefollowing vehicle V.

In this manner, the display video data generating unit 34 sets theclipping area of the captured video data 110A so as to include the lowerend portion B of the following vehicle V identified by the identifyingunit 33, and generates the display video data 110B by performingclipping from the captured video data 110A. The clipping area is thefirst clipping area A1 or the second clipping area A2.

The display video data generating unit 34 repeats the above-describedprocess for every frame or for every certain number of frames.

The display controller 35 causes the rearview monitor 3 to display thedisplay video data 110B generated by the display video data generatingunit 34.

Next, a flow of a process performed by the controller 30 will bedescribed with reference to FIG. 7. FIG. 7 is a flowchart illustrating aflow of the process performed by the controller 30 of the on-vehicledisplay controller 10 of the on-vehicle display system 1 according tothe first embodiment.

The controller 30 detects the following vehicle V in the captured videodata 110A (Step S11). More specifically, the controller 30 causes thedetecting unit 32 to detect the following vehicle V in the capturedvideo data 110A.

The controller 30 identifies the lower end portion B of the followingvehicle V in the captured video data 110A (Step S12). More specifically,the controller 30 causes the identifying unit 33 to identify the lowerend portion B of the following vehicle V that is detected by thedetecting unit 32 in the captured video data 110A.

The controller 30 determines whether the lower end portion B of thefollowing vehicle V is identified (Step S13). More specifically, thecontroller 30 causes the identifying unit 33 to determine whether thelower end portion B of the following vehicle V is identified in thecaptured video data 110A. In other words, the controller 30 causes theidentifying unit 33 to determine whether the lower end portion B of thefollowing vehicle V is included in the captured video data 110A. If theidentifying unit 33 determines that the lower end portion B of thefollowing vehicle V is not identified (NO at Step S13), the controller30 proceeds to Step S15. If the identifying unit 33 determines that thelower end portion B of the following vehicle V is identified (YES atStep S13), the controller 30 proceeds to Step S14.

The controller 30 determines whether the lower end portion B of thefollowing vehicle V is deviated from the first clipping area A1 (StepS14). More specifically, the controller 30 causes the display video datagenerating unit 34 to determine whether the lower end portion B of thefollowing vehicle V is deviated from the first clipping area A1 in thecaptured video data 110A. If the display video data generating unit 34determines that the lower end portion B of the following vehicle V isnot deviated from the first clipping area A1 (NO at Step S14), thecontroller 30 proceeds to Step S15. If the display video data generatingunit 34 determines that the lower end portion B of the following vehicleV is deviated from the first clipping area A1 (YES at Step S14), thecontroller 30 proceeds to Step S16.

The controller 30 sets the first clipping area A1 as the clipping area(Step S15). More specifically, the controller 30 causes the displayvideo data generating unit 34 to set the first clipping area A1 as theclipping area.

The controller 30 sets the second clipping area A2 as the clipping area(Step S16). More specifically, the controller 30 causes the displayvideo data generating unit 34 to set the second clipping area A2. Thesecond clipping area A2 is an area that includes a predetermined numberof pixels that are present below the lower end portion B of thefollowing vehicle V.

The controller 30 generates the display video data 110B by clipping theclipping area (Step S17). More specifically, the controller 30 causesthe display video data generating unit 34 to generate the display videodata 110B by clipping the clipping area.

The controller 30 outputs the display video data 110B (Step S18). Morespecifically, the controller 30 causes the display controller 35 tocause the rearview monitor 3 to display the display video data 110B.

With reference to FIG. 4 and FIG. 8, a detailed example of the processperformed by the controller 30 will be described. FIG. 8 is a diagramillustrating another example of the captured video data obtained throughimaging by the imager 2 of the on-vehicle display system 1 according tothe first embodiment.

In the case of the captured video data 110A illustrated in FIG. 4, bothof the lower end portions B of the two following vehicles V that appearin the captured video data 110A are located inside the first clippingarea A1. The following vehicle V that appears in the center of thecaptured video data 110A illustrated in FIG. 4 is located at a backwardposition separated by about 30 m. At Step S14, the controller 30determines that the lower end portion B of the following vehicle V isnot deviated from the first clipping area A1 (NO at Step S14). At StepS15, the controller 30 sets the first clipping area A1 as the clippingarea. At Step S17, the controller 30 generates the display video data110B by clipping the first clipping area A1. At Step S18, the controller30 causes the rearview monitor 3 to display the display video data 110Billustrated in FIG. 5.

In the case of the captured video data 110A illustrated in FIG. 8, thelower end portion B of the following vehicle V located in the centeramong the two following vehicles V that appear in the captured videodata 110A is deviated from the first clipping area A1. The followingvehicle V that appears in the center of the captured video data 110Aillustrated in FIG. 8 is located at a backward position separated byabout 10 m. At Step S14, the controller 30 determines that the lower endportion B of the following vehicle V is deviated from the first clippingarea A1 (YES at Step S14). At Step S16, the controller 30 sets thesecond clipping area A2 as the clipping area. At Step S17, thecontroller 30 generates the display video data 110B by clipping thesecond clipping area A2. At Step S18, the controller 30 causes therearview monitor 3 to display the display video data 110B illustrated inFIG. 9.

Specifically, as illustrated in FIG. 9, the controller 30 clips an areaincluding the lower end portion B of the following vehicle V anddisplays the area on a display surface of the rearview monitor 3. FIG. 9is a diagram illustrating another example of video displayed on therearview monitor 3 of the on-vehicle display system 1 according to thefirst embodiment. Specifically, an area that is shifted downward so asto include the lower end portion B of the following vehicle V is clippedas the display video data 110B.

In this manner, if the controller 30 determines that the lower endportion B of the following vehicle V is deviated from the first clippingarea A1, the on-vehicle display system 1 causes the rearview monitor 3to display the display video data 110B that is generated by clipping thesecond clipping area A2 that is obtained by shifting the first clippingarea A1 downward. In other words, if the controller 30 determines thatthe lower end portion B of the following vehicle V is deviated from thefirst clipping area A1, the on-vehicle display system 1 displays thedisplay video data 110B including the lower end portion B of thefollowing vehicle V.

As described above, according to the first embodiment, if it isdetermined that the lower end portion B of the following vehicle V isdeviated from the first clipping area A1, it is possible to cause therearview monitor 3 to display the display video data 110B that isgenerated by clipping the second clipping area A2 that is obtained byshifting the first clipping area A1 downward. In other words, if thecontroller 30 determines that the lower end portion B of the followingvehicle V is deviated from the first clipping area A1, the on-vehicledisplay system 1 can display the display video data 110B including thelower end portion B of the following vehicle V.

In this manner, according to the first embodiment, the lower end portionB of the following vehicle V is displayed on the display surface of therearview monitor 3. Further, according to the first embodiment, thelower end portion B of the following vehicle V and a road surface underthe following vehicle V are displayed on the display surface of therearview monitor 3. Therefore, in the first embodiment, a driver canaccurately recognize a distance to the following vehicle V according toa relative relationship with the following vehicle V while considering apositional relationship between the lower end portion B of the followingvehicle V and the road surface integrally.

As described above, according to the first embodiment, it is possible toaccurately recognize a distance to the following vehicle V even with useof an electronic rearview mirror that displays a real image.

As an opposite example, a case will be described in which the firstclipping area A1 is adopted as the clipping area in the captured videodata 110A illustrated in FIG. 8. In this case, the first clipping areaA1 is clipped from the captured video data 110A, and the display videodata 110B as illustrated in FIG. 10 is displayed on the display surfaceof the rearview monitor 3. FIG. 10 is a diagram illustrating an exampleof video displayed on the rearview monitor 3. In the display video data110B illustrated in FIG. 10, the lower end portion B of the followingvehicle V is not displayed on the display surface of the rearviewmonitor 3. Therefore, it is impossible for a driver to compare the lowerend portion B of the following vehicle V and a road surface that isadopted as a comparison target, thus it is difficult for the driver toaccurately recognize a distance to the following vehicle V.

Second Embodiment

With reference to FIG. 11 and FIG. 12, an on-vehicle display system 1Aaccording to a second embodiment will be described. FIG. 11 is a blockdiagram illustrating a configuration example of the on-vehicle displaysystem 1A according to the second embodiment. FIG. 12 is a flowchartillustrating a flow of a process performed by a controller 30A of anon-vehicle display controller 10A of the on-vehicle display system 1Aaccording to the second embodiment. A basic configuration of theon-vehicle display system 1A is the same as the on-vehicle displaysystem 1 of the first embodiment. In the following description, the samecomponents as those of the on-vehicle display system 1 are denoted bythe same or corresponding reference signs, and detailed explanationthereof will be omitted.

The on-vehicle display system 1A of the second embodiment is differentfrom the on-vehicle display system 1 of the first embodiment in that itfurther includes an adjacency determining unit 36A in addition to thecomponents of the on-vehicle display system 1 of the first embodiment.

A controller 30A includes the video data acquiring unit 31, thedetecting unit 32, the identifying unit 33, the display video datagenerating unit 34, the display controller 35, and the adjacencydetermining unit 36A.

The adjacency determining unit 36A determines that the following vehicleV detected by the detecting unit 32 is located close to the vehicle 100.For example, when a size of the detected following vehicle V in avehicle-width direction is equal to or larger than a predeterminedpercent of a size of the captured video data 110A in a width direction,or when the number of pixels of the following vehicle V in thevehicle-width direction is equal to or larger than a predeterminedpercent of the number of pixels of the captured video data 110A in thewidth direction, the adjacency determining unit 36A determines that thefollowing vehicle V is located close to the vehicle 100. Thepredetermined percent used to determine that the following vehicle V islocated close to the vehicle 100 may be changed depending on a type ofthe following vehicle V. The adjacency determining unit 36A outputsdetermination results to the identifying unit 33.

Alternatively, for example, when a distance between the vehicle 100 andthe following vehicle V is equal to or shorter than a predetermineddistance, the adjacency determining unit 36A may determine that thefollowing vehicle V is located close to the vehicle 100. The distancebetween the vehicle 100 and the following vehicle V can be obtained byidentifying a ground contact position that is based on the contour ofthe detected following vehicle V when the detecting unit 32 detects thefollowing vehicle V in the captured video data 110A, and then using apositional relationship of the ground contact position in the capturedvideo data 110A. Alternatively, the distance between the vehicle 100 andthe following vehicle V can be calculated based on a size of an image ofthe following vehicle V that appears in the captured video data 110A anda size of the following vehicle V that is stored in the recognitiondictionary storage unit 200. Further, the adjacency determining unit 36Amay determine that the following vehicle V is located close to thevehicle 100 by using a distance between the vehicle 100 and thefollowing vehicle V that is measured by radar or the like (notillustrated).

While the adjacency determining unit 36A determines whether the distancebetween the vehicle 100 and the following vehicle V is short, it may bepossible to determine whether the following vehicle V is approaching thevehicle 100. For example, when the size of the detected followingvehicle V in the vehicle-width direction has increased with each imagingframe of the captured video data 110A, and if the size becomes equal toor larger than a predetermined percent of the size of the captured videodata 110A in the width direction, or if the number of pixels of thefollowing vehicle V in the vehicle-width direction becomes equal to orlarger than a predetermined percent of the number of pixels of thecaptured video data 110A in the width direction, the adjacencydetermining unit 36A determines that the following vehicle V isapproaching the vehicle 100. Further, the adjacency determining unit 36Amay determine that the following vehicle V is approaching the vehicle100 by using a distance between the vehicle 100 and the followingvehicle V that is measured by radar or the like (not illustrated).

Next, with reference to FIG. 12, a flow of a process performed by thecontroller 30A will be described. The processes at Step S21 and Step S23to Step S29 are the same as the processes at Step S11 to Step S18 in theflowchart illustrated in FIG. 7.

The controller 30A determines whether the following vehicle V in thecaptured video data 110A is located at a close position (Step S22). Morespecifically, when the adjacency determining unit 36A determines thatthe size of the detected following vehicle V in the vehicle-widthdirection is equal to or larger than a predetermined percent of the sizeof the captured video data 110A in the width direction, or when thenumber of pixels of the following vehicle V in the vehicle-widthdirection is equal to or larger than a predetermined percent of thenumber of pixels of the captured video data 110A in the width direction,the controller 30A determines that the following vehicle V is locatedclose to the vehicle 100. Alternatively, for example, when the adjacencydetermining unit 36A determines that the distance between the vehicle100 and the following vehicle V is equal to or shorter than apredetermined distance, the controller 30A determines that the followingvehicle V is located close to the vehicle 100. If it is determined thatthe following vehicle V in the captured video data 110A is located atthe close position (YES at Step S22), the controller 30A proceeds toStep S23. If it is determined that the following vehicle V in thecaptured video data 110A is not located at the close position (NO atStep S22), the controller 30A proceeds to Step S26. In the process atStep S22, it may be possible to determine whether the following vehicleV is approaching, instead of determining whether the following vehicle Vis located at the close position.

With this configuration, when the controller 30A determines that thefollowing vehicle V is located at the close position, the on-vehicledisplay system 1A causes the controller 30A to determine whether thelower end portion B of the following vehicle V is deviated from thefirst clipping area A1.

As described above, according to the second embodiment, when it isdetermined that the following vehicle V is located at the closeposition, it is possible to determine whether the lower end portion B ofthe following vehicle V is deviated from the first clipping area A1.Therefore, according to the second embodiment, it is possible to reduceload on the process performed by the controller 30A.

Third Embodiment

With reference to FIG. 13 to FIG. 16, an on-vehicle display system 1according to a third embodiment will be described. FIG. 13 is aflowchart illustrating a flow of a process performed by a controller ofan on-vehicle display controller of the on-vehicle display systemaccording to the third embodiment. FIG. 14 is a diagram illustrating anexample of captured video data obtained through imaging by an imager ofthe on-vehicle display system according to the third embodiment. FIG. 15is a diagram illustrating an example of video displayed on a rearviewmonitor of the on-vehicle display system according to the thirdembodiment. FIG. 16 is a diagram illustrating another example of videodisplayed on the rearview monitor of the on-vehicle display systemaccording to the third embodiment.

In the on-vehicle display system 1 according to the third embodiment,the controller 30 performs a process different from the process of thefirst embodiment.

When it is determined that an upper end portion U of the followingvehicle V identified by the identifying unit 33 is deviated from thesecond clipping area A2 of the captured video data 110A, the displayvideo data generating unit 34 generates vertically-split display videodata 110B. The vertically-split display video data 110B is video inwhich lower video 110B1 that includes the lower end portion B of thefollowing vehicle V and upper video 110B2 that includes the upper endportion U of the following vehicle V are synthesized. The lower video110B1 is video obtained by clipping the second clipping area A2 thatincludes the lower end portion B of the following vehicle V. The uppervideo 110B2 is video obtained by clipping an area including apredetermined number of pixels that are present above the upper endportion U of the following vehicle V. A ratio between the lower video110B1 and the upper video 110B2 in the display video data 110B is set inadvance. In the third embodiment, for example, the ratio between thelower video 110B1 and the upper video 110B2 is 1:2. In other words, inthe third embodiment, a lower one-third of the display video data 110Bcorresponds to the lower video 110B1, and upper two-thirds of thedisplay video data 110B correspond to the upper video 110B2.

Next, with reference to FIG. 13, a flow of a process performed by thecontroller 30 will be described. The processes at Step S31 to Step S36,Step S38, and Step S40 are the same as the processes at Step S11 to StepS18 in the flowchart illustrated in FIG. 7.

The controller 30 determines whether the upper end portion U of thefollowing vehicle V is deviated from the second clipping area A2 (StepS37). More specifically, the controller 30 causes the display video datagenerating unit 34 to determine whether the upper end portion U of thefollowing vehicle V is deviated from the second clipping area A2 in thecaptured video data 110A. If the display video data generating unit 34determines that the upper end portion U of the following vehicle V isnot deviated from the second clipping area A2 (NO at Step S37), thecontroller 30 proceeds to Step S38. If it is determined that the upperend portion U of the following vehicle V is deviated from the secondclipping area A2 (YES at Step S37), the controller 30 proceeds to StepS39.

The controller 30 generates the vertically-split display video data 110B(Step S39). More specifically, the controller 30 causes the displayvideo data generating unit 34 to generate the display video data 110B,in which the lower video 110B1 that includes the lower end portion B ofthe following vehicle V and the upper video 110B2 that includes theupper end portion U of the following vehicle V are synthesized. In thedisplay video data 110B, the lower part corresponds to the lower video110B1 and the upper part corresponds to the upper video 110B2.

With reference to FIG. 14 to FIG. 16, a detailed example of the processperformed by the controller 30 will be described.

In the case of the captured video data 110A illustrated in FIG. 14, thelower end portion B of the following vehicle V that appears in thecaptured video data 110A is deviated from the first clipping area A1.The upper end portion U of the following vehicle V that appears in thecaptured video data 110A illustrated in FIG. 14 is deviated from thesecond clipping area A2. The following vehicle V that appears in thecaptured video data 110A illustrated in FIG. 14 is located at a backwardposition separated by about 5 m to 10 m. At Step S34, the controller 30determines that the lower end portion B of the following vehicle V isdeviated from the first clipping area A1 (YES at Step S34). At Step S36,the controller 30 sets the second clipping area A2 as the clipping area.At Step S37, the controller 30 determines that the upper end portion Uof the following vehicle V is deviated from the second clipping area A2(YES at Step S37). At Step S39, the controller 30 generates thevertically-split display video data 110B. At Step S40, the controller 30causes the rearview monitor 3 to display the display video data 110Billustrated in FIG. 15.

As described above, according to the third embodiment, thevertically-split display video data 110B is generated so as to includethe lower end portion B and the upper end portion U of the followingvehicle V identified by the identifying unit 33 as illustrated in FIG.15. In this manner, according to the third embodiment, it is possible todisplay the vertically-split display video data 110B including the lowerend portion B and the upper end portion U of the following vehicle V onthe display surface of the rearview monitor 3. Therefore, according tothe third embodiment, a driver can accurately recognize a distance tothe following vehicle V according to a relative relationship with thefollowing vehicle V while considering the lower end portion B of thefollowing vehicle V and information on the size of a surrounding objectthat is adopted as a comparison target, such as a white line drawn onthe road surface, integrally. Further, according to the thirdembodiment, since the interior of the following vehicle V appears in thedisplay video data 110B illustrated in FIG. 15, is possible to view adriver of the following vehicle V.

In contrast, in the first embodiment, when the captured video data 110Aillustrated in FIG. 14 is used, the display video data 110B asillustrated in FIG. 16 is displayed. Therefore, the display video data110B does not include the upper end portion U of the following vehicleV, and it is difficult for the driver to accurately recognize a distanceto the following vehicle V. Further, because the upper end portion U isnot included, it is difficult to view the driver of the followingvehicle V.

Fourth Embodiment

With reference to FIG. 17 to FIG. 19, the on-vehicle display system 1according to a fourth embodiment will be described. FIG. 17 is a diagramillustrating an example of captured video data obtained through imagingby an imager of the on-vehicle display system according to the fourthembodiment. FIG. 18 is a flowchart illustrating a flow of a processperformed by a controller of an on-vehicle display controller of theon-vehicle display system according to the fourth embodiment. FIG. 19 isa flowchart illustrating another example of the flow of the processperformed by the controller of the on-vehicle display controller of theon-vehicle display system according to the fourth embodiment.

The on-vehicle display system 1 according to the fourth embodiment isdifferent from that of the first embodiment in that wheel portions B1 ofthe following vehicle V are identified as a lower part of the vehicle.

The identifying unit 33 identifies the wheel portions B1 of thefollowing vehicle V as the lower part of the following vehicle V that isdetected by the detecting unit 32 in the captured video data 110A. Morespecifically, the identifying unit 33 identifies the wheel portions B1of the following vehicle V in the captured video data 110A. The wheelportions B1 are portions that are recognized as wheels by performing animage recognition process on the captured video data 110A. The wheelportions B1 are detected as planes with certain areas. In FIG. 17, thewheel portions are areas indicated by oblique lines. In the fourthembodiment, the identifying unit 33 identifies front wheels of thefollowing vehicle V in the captured video data 110A.

When it is impossible to identify the ground contact portions of thefront wheels of the following vehicle V, the identifying unit 33 mayidentify the lower end portion of the body of the following vehicle V inthe captured video data 110A.

The display video data generating unit 34 sets a clipping area of thecaptured video data 110A so as to include the wheel portions B1 of thefollowing vehicle V identified by the identifying unit 33, and generatesthe display video data 110B by performing clipping from the capturedvideo data 110A.

If the wheel portions B1 of the following vehicle V in the capturedvideo data 110A is located outside the first clipping area A1 in thecaptured video data 110A, the display video data generating unit 34determines that the wheel portions B1 are deviated from the firstclipping area A1. If it is determined that the wheel portions B1 of thefollowing vehicle V are deviated from the first clipping area A1, thedisplay video data generating unit 34 sets, as the clipping area, thesecond clipping area A2 that includes the wheel portions B1 of thefollowing vehicle V. Alternatively, the second clipping area A2 may beset so as to include a road surface on which the wheel portions B1 ofthe following vehicle V are grounded.

Next, with reference to FIG. 18, a flow of a process performed by thecontroller 30 will be described. The processes at Step S51 and Step S55to S58 are the same as the processes at Step S11 and Step S15 to StepS18 in the flowchart illustrated in FIG. 7.

The controller 30 identifies the wheel portions B1 of the followingvehicle V in the captured video data 110A (Step S52). More specifically,the controller 30 causes the identifying unit 33 to identify, in thecaptured video data 110A, the wheel portions B1 of the following vehicleV detected by the detecting unit 32.

The controller 30 determines whether the wheel portions B1 of thefollowing vehicle V are identified (Step S53). The controller 30 causesthe identifying unit 33 to identify whether the captured video data 110Aincludes the wheel portions B1 of the following vehicle V. If theidentifying unit 33 determines that the wheel portions B1 of thefollowing vehicle V are not identified (NO at Step S53), the controller30 proceeds to Step S55. If the identifying unit 33 determines that thewheel portions B1 of the following vehicle V are identified (YES at StepS53), the controller 30 proceeds to Step S54.

The controller 30 determines whether the wheel portions B1 of thefollowing vehicle V are deviated from the first clipping area A1 (StepS54). If the display video data generating unit 34 determines that thewheel portions B1 of the following vehicle V are not deviated from thefirst clipping area A1 (NO at Step S54), the controller 30 proceeds toStep S55. If the display video data generating unit 34 determines thatthe wheel portions B1 of the following vehicle V are deviated from thefirst clipping area A1 (YES at Step S54), the controller 30 proceeds toStep S56.

Alternatively, the controller 30 may perform a process as illustrated inFIG. 19. The processes from Step S61 to Step S63 and Step S68 to StepS71 are the same as the processes from Step S51 to Step S53 and Step S55to Step S58 in the flowchart illustrated in FIG. 18.

If the wheel portions B1 of the following vehicle V are identified (YESat Step S63), the controller 30 sets the wheel portions B1 of thefollowing vehicle V as a lower part (Step S64).

If the wheel portions B1 of the following vehicle V are not identified(NO at Step S63), the controller 30 determines whether the lower endportion of the body of the following vehicle V is identified (Step S65).The controller 30 causes the identifying unit 33 to determine whetherthe captured video data 110A includes the lower end portion of the bodyof the following vehicle V. If the identifying unit 33 determines thatthe lower end portion of the body of the following vehicle V is notidentified (NO at Step S65), the controller 30 proceeds to Step S68. Ifthe identifying unit 33 determines that the lower end portion of thebody of the following vehicle V is identified (YES at Step S65), thecontroller 30 proceeds to Step S66.

If the lower end portion of the body of the following vehicle V isidentified (YES at Step S65), the controller 30 sets the lower endportion of the body of the following vehicle V as the lower part (StepS66).

The controller 30 determines whether the lower part of the followingvehicle V is deviated from the first clipping area A1 (Step S67). If thedisplay video data generating unit 34 determines that the lower part ofthe following vehicle V is not deviated from the first clipping area A1(NO at Step S67), the controller 30 proceeds to Step S68. If the displayvideo data generating unit 34 determines that the lower part of thefollowing vehicle V is deviated from the first clipping area A1 (YES atStep S67), the controller 30 proceeds to Step S69.

With reference to FIG. 17, a detailed example of the process performedby the controller 30 will be described. In the case of the capturedvideo data 110A illustrated in FIG. 17, the wheel portions B1 of thefollowing vehicle V that is located in the center among the twofollowing vehicles V that appear in the captured video data 110A aredeviated from the first clipping area A1. At Step S54, the controller 30determines that the wheel portions B1 of the following vehicle V aredeviated from the first clipping area A1 (YES at Step S54). At Step S56,the controller 30 sets the second clipping area A2 as the clipping area.At Step S57, the controller 30 generates the display video data 110B byclipping the second clipping area A2. At Step S58, the controller 30causes the rearview monitor 3 to display the display video data 110B.

As described above, according to the fourth embodiment, the wheelportions B1 of the following vehicle V or the lower end portion of thebody of the following vehicle V are/is identified as the lower part ofthe following vehicle V. According to the fourth embodiment, the wheelportions B1 of the following vehicle V or the lower end portion of thebody of the following vehicle V are/is displayed on the display surfaceof the rearview monitor 3. Therefore, according to the fourthembodiment, it is possible to perform displaying such that a driver caneasily recognize a positional relationship between the following vehicleV and the road surface, by displaying a certain part that is located asclose as possible to the road surface among all parts of the followingvehicle V in the captured video data 110A. In this manner, according tothe fourth embodiment, it is possible to accurately recognize a distanceto the following vehicle V even with use of an electronic rearviewmirror that displays a real image.

Fifth Embodiment

With reference to FIG. 20 and FIG. 21, the on-vehicle display system 1according to a fifth embodiment will be described. FIG. 20 is a diagramillustrating an example of captured video data obtained through imagingby an imager of an on-vehicle display system according to the fifthembodiment. FIG. 21 is a flowchart illustrating an example of a flow ofa process performed by a controller of an on-vehicle display controllerof the on-vehicle display system according to the fifth embodiment.

The on-vehicle display system 1 according to the fifth embodiment isdifferent from that of the first embodiment in that an identificationsign portion B2 of the following vehicle V is identified as a lower partof a vehicle. In the fifth embodiment, a license plate is described asan identification sign portion. However, the identification sign portionis not limited to the license plate, but any sign for identifying avehicle is applicable.

The identifying unit 33 identifies the license plate B2 of the followingvehicle V as the lower part of the following vehicle V detected by thedetecting unit 32 in the captured video data 110A. More specifically,the identifying unit 33 performs an image recognition process andidentifies the license plate B2 of the following vehicle V in thecaptured video data 110A. In FIG. 20, the license plate is an areaindicated by oblique lines. In the fifth embodiment, the identifyingunit 33 identifies the license plate B2 on front side of the followingvehicle V in the captured video data 110A.

The display video data generating unit 34 sets a clipping area of thecaptured video data 110A so as to include the license plate B2 of thefollowing vehicle V identified by the identifying unit 33, and generatesthe display video data 110B by performing clipping from the capturedvideo data 110A.

When the license plate B2 of the following vehicle V in the capturedvideo data 110A is located outside the first clipping area A1 in thecaptured video data 110A, the display video data generating unit 34determines that the license plate is deviated from the first clippingarea A1. If it is determined that the license plate B2 of the followingvehicle V is deviated from the first clipping area A1, the display videodata generating unit 34 sets, as a clipping area, the second clippingarea A2 that includes the license plate B2 of the following vehicle V.

Next, a flow of a process performed by the controller 30 will bedescribed with reference to FIG. 21. The processes at Step S81 and StepS86 to Step S92 are the same as the processes at Step S61 and Step S65to Step S71 in the flowchart illustrated in FIG. 19.

The controller 30 identifies the license plate B2 of the followingvehicle V in the captured video data 110A (Step S82). More specifically,the controller 30 causes the identifying unit 33 to identify the licenseplate B2 of the following vehicle V detected by the detecting unit 32 inthe captured video data 110A.

The controller 30 determines whether the license plate B2 of thefollowing vehicle V is identified (Step S83). The controller 30 causesthe identifying unit 33 to determine whether the license plate B2 of thefollowing vehicle V is included in the captured video data 110A. If theidentifying unit 33 determines that the license plate B2 of thefollowing vehicle V is not identified (NO at Step S83), the controller30 proceeds to Step S86. If the identifying unit 33 determines that thelicense plate B2 of the following vehicle V is identified (YES at StepS83) the controller 30 proceeds to Step S84.

The controller 30 determines whether the license plate B2 of thefollowing vehicle V is located in the lower side of the vehicle body(Step S84). The controller 30 determines whether the license plate B2 ofthe following vehicle V is located in the lower side of the body of thefollowing vehicle V in the captured video data 110A. If it is determinedthat the license plate B2 of the following vehicle V is not located inthe lower side of the vehicle body (NO at Step S84), the controller 30proceeds to Step S86. If it is determined that the license plate B2 ofthe following vehicle V is located in the lower side of the vehicle body(YES at Step S84), the controller 30 proceeds to Step S85.

If it is determined that the license plate B2 of the following vehicle Vis located in the lower side of the vehicle body (YES at Step S84), thecontroller 30 sets the license plate B2 of the following vehicle V asthe lower part (Step S85).

With reference to FIG. 20, a detailed example of the process performedby the controller 30 will be described. In the case of the capturedvideo data 110A illustrated in FIG. 20, the license plate B2 of thefollowing vehicle V that is located in the center among the twofollowing vehicles V that appear in the captured video data 110A isdeviated from the first clipping area A1. At Step S88, the controller 30determines that the license plate B2 of the following vehicle V isdeviated from the first clipping area A1 (YES at Step S88). At Step S89,the controller 30 sets the second clipping area A2 as the clipping area.At Step S91, the controller 30 generates the display video data 110B byclipping the second clipping area A2. At Step S92, the controller 30causes the rearview monitor 3 to display the display video data 110B.

As described above, according to the fifth embodiment, the license plateB2 of the following vehicle V is identified as the lower part of thevehicle. According to the fifth embodiment, the license plate B2 of thefollowing vehicle V is displayed on the display surface of the rearviewmonitor 3. Therefore, according to the fifth embodiment, it is possibleto perform displaying such that a driver can easily recognize apositional relationship between the following vehicle V and the roadsurface, by displaying a certain part that is located as close aspossible to the road surface among all parts of the following vehicle Vin the captured video data 110A. In this manner, according to the fifthembodiment, it is possible to accurately recognize a distance to thefollowing vehicle V even with use of an electronic rearview mirror thatdisplays a real image.

The components of the on-vehicle display system 1 illustrated in thedrawings are conceptual function, and need not be physically configuredin the manner illustrated in the drawings. In other words, specificforms of the apparatuses are not limited to those illustrated in thedrawings, and all or part of the apparatuses may be functionally orphysically distributed or integrated in arbitrary units depending onvarious loads or use conditions.

The configuration of the on-vehicle display system 1 is realized assoftware by, for example, a program or the like loaded on a memory. Inthe embodiments described above, it is explained that the functionalblocks are implemented by cooperation with hardware or software. Inother words, the functional blocks are realized in various forms usingonly hardware, using only software, or using a combination of hardwareand software.

The components described above include one that can easily be thought ofby a person skilled in the art and one that is practically identical.Further, the configurations described above may be combinedappropriately. Furthermore, within the scope not departing from the gistof the present disclosure, various omission, replacement, andmodifications of the components may be made.

The controller 30 may determine whether to perform the process in theflowchart illustrated in FIG. 7, based on the current position of thevehicle 100 before Step S11 of the flowchart illustrated in FIG. 7. Forexample, the controller 30 includes a current location data acquiringunit that acquires a current location of the vehicle 100 and asurrounding situation data acquiring unit that acquires a surroundingsituation including map information, and if the vehicle 100 istravelling on a predetermined road, such as expressway, the controller30 may not perform the process in the flowchart illustrated in FIG. 7.Alternatively, the controller 30 may include the current location dataacquiring unit and the surrounding situation data acquiring unit, and ifthe vehicle 100 is travelling at a predetermined speed or higher, thecontroller 30 may not perform the process in the flowchart illustratedin FIG. 7. In this case, it is less expected that the following vehicleV approaches within, for example, 5 m of the vehicle 100 and the lowerend portion B of the following vehicle V is deviated from the firstclipping area A1. Consequently, it is possible to reduce load on theprocess performed by the controller 30.

The controller 30 may set the second clipping area A2 as the clippingarea at Step S16 when the determination condition is continuouslysatisfied for a certain period of time at Step S13 in the flowchartillustrated in FIG. 7. With this operation, the on-vehicle displaysystem 1 can prevent an unnecessary change of the video displayed on therearview monitor 3. In this manner, the on-vehicle display system 1 canappropriately check surroundings of the vehicle 100.

The controller 30 may determine whether a relative speed of thefollowing vehicle V and the vehicle 100, or a moving state such as amoving direction of the following vehicle V satisfy predeterminedconditions, in addition to the determination at Step S22 in theflowchart illustrated in FIG. 12 or instead of the determination at StepS22. Further, for example, when the detecting unit 32 detects that therelative speed of the following vehicle V and the vehicle 100 is equalto or higher than a predetermined value, the controller 30 may determinethat the moving state satisfies a predetermined condition and performthe processes from Step S23. Here, the relative speed of the followingvehicle V and the vehicle 100 can be calculated based on a change in thesize of the image of the following vehicle V in each of the frames inthe captured video data 110A. Furthermore, for example, when thedetecting unit 32 detects that the moving direction of the followingvehicle V is a direction approaching the vehicle 100, the controller 30may determine that the moving state satisfies a predetermined conditionand perform the processes from Step S23. The controller 30 may performdetermination using a combination of the determination conditions asdescribed above. Through the operation as described above, theon-vehicle display system 1 can appropriately check surroundings of thevehicle 100.

When setting the second clipping area A2 as the clipping area, thecontroller 30 may display the display video data 110B in a translucentcolor having a predetermined translucency. With this operation, theon-vehicle display system 1 can easily confirm that the rearview monitor3 displays the display video data 110B that is obtained by clipping thesecond clipping area A2. In this manner, the on-vehicle display system 1can appropriately check surroundings of the vehicle 100.

When the detecting unit 32 detects the following vehicle V, if thefollowing vehicle V has a license plate, the detecting unit 32 may readalphanumeric characters and signs on the license plate and detect thefollowing vehicle V without using a recognition dictionary stored in therecognition dictionary storage unit 200. With this operation, theon-vehicle display system 1 can be configured simply.

Furthermore, in the embodiments described above, a case has beendescribed in which the rearview monitor 3 is configured as an electronicrearview mirror. However, the mode of the rearview monitor 3 is notlimited to the electronic rearview mirror. For example, when the presentapplication is applied for use when the vehicle 100 is moving forward,it is effective that the present application is embodied in theelectronic rearview mirror. When the present application is applied inorder to check a vehicle that is stopped on the rear side of the vehicle100 while the vehicle 100 is stopped or moving backward, the rearviewmonitor 3 may be mounted at any position that can be viewed by a driver,or may be configured as a portable type and placed behind the driver soas to be viewed by the driver while the vehicle is moving backward.

According to the present application, it is possible to easily recognizea distance to a following vehicle.

Although the application has been described with respect to specificembodiments for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

What is claimed is:
 1. An on-vehicle display controller comprising: avideo data acquiring unit configured to acquire captured video dataobtained through imaging by an imager that is configured to imagesurroundings of a vehicle; a detecting unit configured to detect afollowing vehicle in the captured video data; an identifying unitconfigured to identify a lower part of the following vehicle detected bythe detecting unit; a display video data generating unit configured togenerate display video data by clipping a predetermined clipping areafrom the captured video data, and to set, in response to determiningthat the lower part of the following vehicle identified by theidentifying unit has deviated from the predetermined clipping area, aclipping area of the captured video data so as to include the lower partof the following vehicle, and generate the display video data byclipping the clipping area from the captured video data; and a displaycontroller configured to cause a display used in the vehicle to displaythe display video data generated by the display video data generatingunit.
 2. The on-vehicle display controller according to claim 1, whereinthe identifying unit identifies a lower end portion of the followingvehicle as the lower part of the following vehicle detected by thedetecting unit.
 3. The on-vehicle display controller according to claim1, wherein the identifying unit identifies wheel portions of thefollowing vehicle as the lower part of the following vehicle detected bythe detecting unit.
 4. The on-vehicle display controller according toclaim 1, wherein the identifying unit identifies an identification signportion of the following vehicle as the lower part of the followingvehicle detected by the detecting unit.
 5. The on-vehicle displaycontroller according to claim 1, wherein the display video datagenerating unit sets the clipping area by shifting the predeterminedclipping area in a direction that causes the lower part of the followingvehicle to be included in the clipping area.
 6. The on-vehicle displaycontroller according to claim 1, wherein the display video datagenerating unit sets the clipping area of the captured video data so asto include a road surface that is present below the lower part of thefollowing vehicle identified by the identifying unit.
 7. The on-vehicledisplay controller according to claim 1, wherein the display video datagenerating unit sets the clipping area such that the lower part of thefollowing vehicle detected by the detecting unit is not deviated from alower side of the clipping area of the captured video data.
 8. Theon-vehicle display controller according to claim 1, wherein in responseto determining that a plurality of following vehicles detected by thedetecting unit are present, the identifying unit identifies a lower partof a following vehicle, of the plurality of following vehicles, that islocated closest to a rear end portion of the vehicle, and the displayvideo data generating unit sets the clipping area of the captured videodata so as to include the lower part of the following vehicle that islocated closest to the rear end portion of the vehicle.
 9. Theon-vehicle display controller according to claim 1, wherein in responseto detecting that a plurality of following vehicles detected by thedetecting unit are present, the identifying unit identifies a lower partof a following vehicle, of the plurality of following vehicles, that islocated in a most central portion in the captured video data, and thedisplay video data generating unit sets the clipping area of thecaptured video data so as to include the lower part of the followingvehicle located in the most central portion in the captured video data.10. The on-vehicle display controller according to claim 1, furthercomprising: an adjacency determining unit configured to determinewhether the following vehicle detected by the detecting unit is locatedwithin a defined proximity of the vehicle, wherein in response to adetermination by the adjacency determining unit that the followingvehicle detected by the detecting unit is located within the definedproximity of the vehicle, the identifying unit identifies the lower partof the following vehicle detected by the detecting unit.
 11. Theon-vehicle display controller according to claim 10, wherein theadjacency determining unit determines that the following vehicledetected by the detecting unit is located within the defined proximityof the vehicle based on a determination that a width of the followingvehicle is equal to or larger than a predetermined percent of a size ofthe captured video data.
 12. An on-vehicle display system comprising:the on-vehicle display controller according to claim 1; and at least oneof the imager and the display.
 13. An on-vehicle display control methodcomprising steps of: acquiring captured video data obtained throughimaging by an imager that is configured to image surroundings of avehicle; detecting a following vehicle in the captured video data;identifying a lower part of the following vehicle detected by thedetecting; generating display video data by clipping a predeterminedclipping area from the captured video data acquired by the acquiring,and in response to determining that the lower part of the followingvehicle identified by the identifying has deviated from thepredetermined clipping area, setting a clipping area of the capturedvideo data so as to include the lower part of the following vehicleidentified at the identifying; and causing a display in the vehicle todisplay the display video data generated at the generating.
 14. Anon-transitory storage medium that stores a program for causing acomputer serving as an on-vehicle display controller to execute stepsof: acquiring captured video data obtained through imaging by an imagerthat is configured to image surroundings of a vehicle; detecting afollowing vehicle in the captured video data; identifying a lower partof the following vehicle detected by the detecting; generating displayvideo data by clipping a first clipping area from the captured videodata acquired by the acquiring; in response to determining that thelower part of the following vehicle identified by the identifying hasdeviated from the predetermine first area, setting a second clippingarea of the captured video data so as to include the lower part of thefollowing vehicle identified at the identifying; and causing a displayin the vehicle to display the display video data generated at thegenerating.